(...) Confirmed. The arrows and grey button share a common resistor ladder and only one can be detected. But the orange "on" button has an independant circuitry and can be used separately. See keypad schematics in the HDK. Philo (17 years ago, 21-Jan-08, to lugnet.robotics.nxt, FTX)
(...) Actually, I've found that the orange button cannot be used independently, at least not from an NXT-G program. A simple program in NXT-G demonstrates the buttons supercede each other as follows: Right button (lowest priority) Left button Off (...) (17 years ago, 21-Jan-08, to lugnet.robotics.nxt, FTX)